neuro part 1

Question 0

what is the total volume in the skull?

Answer 0

1200-1500 ml

Question 1

what percents of the head do each of these make up:

1. brain
2. csf
3. blood

Answer 1

1. brain=80%
2. csf=10%
3. blood=10%

Question 2

1. how much of the cardiac output does the brain get?
2. what is the blood flow for grams of brain tissue?
3. how much of the total glucose does the brain get?
4. how much of the basal oxygen?
5. How does the brains metabolic consumption rank??

Answer 2

1. 15%
2. 50 mL for every 100g of brain (0.5 cc blood for every 1 gram of brain)
3. 25% of basal glucose (5 mg/100g/min)
4. 20% of basal oxygen
5. the brain has the higest metabolic requirement of any organ

Question 3

what are the 2 divisions of the brain (upper and lower)

Answer 3

supratentorial and infratentorial

Question 4

what is robin hood phenomenon?

Answer 4

the vasoconstriction of vessels in healthy areas of the brain to send blood to injured parts of the brain

Question 5

do these drugs pass the blood brain barrier?

1. heparin?
2. mannitol?
3. atropine?
4. robinol?
5. fentanyl?

Answer 5

1. heparin doesnt cross (ionized/ too big)
2. mannitol doesnt cross (too big)
3. atropine does cross (causes mental changes and pupil changes)
4. robinol doesnt cross (ionized-quaternary ammonium)
5. fentanyl does cross -highly lipid soluble

Question 6

why does a renal patient have LOWER tolerance for narcotics and versed?

Answer 6

the blood brain barrier may be interrupted (D/T prolonged and severe hypertension) so that drugs cross more readily into the brain

Question 7

1. how much CSF does your brain make?

2. what is the spec grav

Answer 7

1. 150 ml (0.3 ml/minute)

2. spec grav 1.002 to 1.009; ph=7.32

Question 8

what does the CSF do?

Answer 8

-protects structures, maintains pH

Question 9

where is CSF made and what is the path of circulation?

Answer 9

a. formed in lateral ventricles by pindinal cells
b. flows thru foramen of monroe into 3rd ventricles
c. flows thru aquadect of silvius into the 4th ventricle
d. into cisterna magnum thru lateral foramen of lushka majendi

Question 10

1. what is an elevated ICP

2. why do you have edema with increased ICP

Answer 10

1. a sustained ICP of 15-20 mmHg
2. increased ICP causes ischemia;
   when ischemia is noted, the vasculature tries to increase blood flow, which increases pressure.

Question 11

1. at what mmHg will you see a shift in the autoregulatory curve?
2. which way will it shift?

Answer 11

1. > 150 mmHg

2. shift to right

Question 12

1. how do you calculate CPP?
2. what is a normal CPP?
3. what is the lowest acceptable CPP?
4. what hemodynamic measurement closely equates to ICP?

Answer 12

1. MAP-ICP
2. 70-80 mmHg
3. 60 mmHg
4. CVP

Question 13

• Cushing’s Reflex?
  1. what is it also called?
  2. what causes it?

Answer 13

1. CNS perfusion reflex
2. when CPP drops less than 50 or ICP >30
   - this drop causes decreases in blood flow
   - which then causes sympathetic system to increase MAP

Question 14

what does stump pressure measure

Answer 14

collateral blood flow to the brain

Question 15

1. what happens with increases in brain activity?

2. what is this called?

Answer 15

1. the more brain activity you have, the metabolic need increases (blood flow and glucose)
2. coupling

Question 16

1. what is brain glucose consumption?
2. what happens when you are anoxic?
3. what does this cause?
4. how long will it take for irreversible brain damage to occur?

Answer 16

1. 5 mg/100g of brain per minute
2. you continue to metabolize glucose using anerobic glycolysis
3. anerobic glycolysis causes release of lactic acid (H+ ions etc. which decreases pH),
   - - this increases blood flow (vasodilation)
   - - this vasodilation increases ICP (this is what causes anoxic brain damage)
4. 3-8 minutes

Question 17

1. at what HCT does optimal brain oxygenation occur
2. what is the whole body’s total resting oxygen consumption (mL/min)
3. what is the brain’s total resting oxygen consumption (% and ml)

Answer 17

1. 30-34%
2. 250 ml/min
3. normal CMRo2 is 20% of resting oxygen consumption (50 ml/min)